According to the Local Co-ordination Committee, an opposition group, since the beginning of the uprising 761 people have been killed in Homs, 594 in Deraa, and 350 in Hama.

Opposition council formed

A group of Syrian activists declared on Thursday a council representing a united front in opposition to al-Assad.

About 140 figures, including exiled opponents and 70 dissidents inside Syria, were chosen as members of the new Syrian National Council, concluding a four-day meeting in the Turkish city of Istanbul.

The council aims to help topple Assad within six months and form an interim government thereafter, Basma Kadmani, a Syrian exile living in France, announced.

"The political vision of the council will give a push to the escalation of the revolutionary work we are seeing," Kadmani said.

"This group, based on previous initiatives, and on what the street is demanding, is calling for the downfall of the regime with all of its limbs."

A popular uprising began in Syria in mid-March and turned violent after Assad's security forces reacted with deadly force.

About 2,600 civilians have been killed so far, according to United Nations estimates, and reports of brutal use of force continue to trickle out of Syria.

Strident call

Ban Ki-moon, the UN secretary-general, made an unusually strident call on Thursday, urging Assad to end the crackdown.

"When he has not been keeping his promises, enough is enough and the international community should really take coherent measures and speak in one voice," Ban said.

Ban has had several telephone conversations with Assad since the protests erupted on March 15, during which the Syrian president repeatedly promised to end the bloody crackdown and institute political reforms.

"These promises have become now broken promises," Ban said.

He said it was up to UN member states and the Security Council to decide what action should be taken after Syria ignored repeated international appeals.

"Protesters will be welcoming [Ban's]remarks," our correspondent said. "However, they will want tougher stance and not words. They need action because, according to them, they have been slaughtered for the past six months.

"I don’t think [the remarks] will have impact on the Syrian leadership to stop the violence. I think the leadership in Syria is betting on the fact that the international community, mainly the Security Council, is divided."

While the US, UK and France have called on Assad to step down and imposed sanctions against him and other figures believed to be involved in the deadly crackdowns, Russia and China have blocked efforts at the Security Council to impose more sanctions against Syria.